Centuries before the Era of Upheaval, Aec'Letec was freed from the Abyss and released onto Toril by cultists that worshiped him as a god. He was defeated shortly thereafter, by Durlag Trollkiller and Arlo of Clan Stoneblade. While the latter wound up dying from wounds he incurred in this battle, together they managed to imprison the tanar'ri's "essence" within the artifact known as the Soultaker dagger. The dagger was then lost to time within Durlag's Tower.
In the Year of the Gauntlet, 1369 DR, Tracea Carol and their fellow cultists sought the Soultaker dagger to free Aec'Letec from his imprisonment and let him loose upon Faerûn in Ulgoth's Beard. Hurgan Stoneblade went searching after the dagger as well, in order to put a stop to their plan.